Some people dread visiting their in-laws. Not me. I am lucky enough to have in-laws who live in Northern California and love good food and drink. When we visit, they are always turning me on to interesting bottles that I know we'll eventually be seeing on the East Coast.

Over the years, my wife's parents first poured me the high-end vermouth Vya from Quady, tipped me off to excellent-value zinfandels from Amador County and pointed me toward amazing fruit brandies from St. George Spirits in Alameda. But I am most indebted to them for introducing me, about five years ago, to something they had brought back from Italy: Barolo Chinato, a bitter, lush, complex digestivo from Piemonte. It was the finest after-dinner drink I'd tasted, and I've been hooked ever since.

The problem, of course, has been that outside Italy (and then California) it has been difficult to track down. Until recently, that is, when I've seen it popping up audaciously on cocktail menus at places such as Bar Pilar.

The spirit is produced in much the same way as its Piemontese cousin, vermouth, but with one big difference. Vermouth generally begins with a simple, tasteless white wine to which the herbs are added. Barolo Chinato begins with Barolo, Italy's greatest wine, made with the nebbiolo grapes of the region. The result is a smooth, spicy drink with just a kiss of quinine on the tongue.

There is some question as to who invented Barolo Chinato. In the 19th century, many pharmacists and chefs in and around Turin were experimenting with vermouths and other fortified wines. One of them, Giuseppe Cappellano, is often credited as Barolo Chinato's creator, and the Cappellano brand is available in the United States.

But Barolo Chinato is also claimed by Giulio Cocchi, a Tuscan pastry chef who came to Asti and, inspired by the region's vermouth industry, soon invented his own formula in 1891.

Cocchi's was the Barolo Chinato I fell in love with, so I decided to visit its producer on a recent trip to Piemonte. The brand name Giulio Cocchi is well known in Italy for its Asti spumante, but the company also continues to make its founder's special formula. "We like to think the Barolo Chinato concept came because he put together the world of vermouth in Piemonte with the world of the Tuscan monasteries and their use of spices and herbs," says Roberto Bava, fourth-generation winemaker with Bava Winery, which now owns Giulio Cocchi. "His formula was, and still is, very complex. One of my brothers knows the formula. It is in an old booklet, handwritten by Giulio Cocchi, and it's in a bank vault."

In the 1920s, Giulio Cocchi opened a chain of Barolo Chinato bars in cities including Turin and Milan and as far away as Caracas, Venezuela. (The Turin location still exists.) But by the 1960s and 1970s, Barolo Chinato had gone out of fashion, swept away by the popular tide of amari, mass-market vermouths and aperitivi such as Punt e Mes that began to flood the Italian market. Cocchi persisted, selling its spumante, and eventually was bought by the Bava family in 1977. But its Barolo Chinato languished for decades.

That is, until the all-important chocolate-Chinato connection came to light. Bava is president of something he referred to as the "Italian Chocolate Association." Several years ago, he says, the association's members began searching for the best after-dinner drink to pair with fine chocolate, another Piemonte specialty. After supposedly rigorous testing, Bava says, "We learned that Barolo Chinato was the absolute best match for chocolate." Regardless of how subjective that research must have been, it seems to have been a eureka moment in the history of food and drink pairings because, believe me, it is true. "Now," Bava says, "if you ask anyone in Italy, 'What do you pair with chocolate?' They will say, 'Barolo Chinato.' "

Bava says the chocolate-pairing concept has saved Barolo Chinato from extinction and spurred other producers to put their versions on the market. "I'm proud of this. It's probably the only idea in this life that I will leave behind," he says, with a wink.

Of course, in the United States, where after-dinner drinks are still a puzzle to most people, we judge the viability of spirits by their application in cocktails.

Enter Adam Bernbach of Bar Pilar, who has been serving terrific Chinato-based cocktails for some time. "I love the stuff. I'm addicted to it," Bernbach says. "Its supporters at the bar have become pretty vocal about it." He uses Marcarini brand Barolo Chinato, which is available in the District through Bacchus distributors. (If your liquor store doesn't carry it, have them order it.)

Bernbach showcases Barolo Chinato in his Darkside cocktail, which he first started serving at his Tuesday night cocktail sessions. The Darkside, to me, is an instant classic. The Chinato plays exceptionally well with Plymouth gin's juniper and secondary notes of citrus and cardamom and with the floral, gentian-based Peychaud bitters. It's perhaps the finest new-school cocktail served in Washington, a perfect match for one of the finest spirits in the world.